21055433647 has 16 divisors (see below), whose sum is σ = 21927628800. Its totient is φ = 20196011520.

The previous prime is 21055433639. The next prime is 21055433653. The reversal of 21055433647 is 74633455012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21055433647 - 2³ = 21055433639 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055433677) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1852879 + ... + 1864207.

It is an arithmetic number, because the mean of its divisors is an integer number (1370476800).

Almost surely, 2^21055433647 is an apocalyptic number.

21055433647 is a deficient number, since it is larger than the sum of its proper divisors (872195153).

21055433647 is a wasteful number, since it uses less digits than its factorization.

21055433647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11886.

The product of its (nonzero) digits is 302400, while the sum is 40.

Adding to 21055433647 its reverse (74633455012), we get a palindrome (95688888659).

The spelling of 21055433647 in words is "twenty-one billion, fifty-five million, four hundred thirty-three thousand, six hundred forty-seven".